南丰蜜橘β-胡萝卜素羟化酶基因内含子的鉴定和分析

Identification and Analysis of the Introns of β-carotene Hydroxylase Gene from Nanfeng Orange(Citrus reticulata Blanco var. kinokuni(Tanaka)H.H.Hu)

植物β-胡萝卜素羟化酶(简称β-羟化酶)是玉米黄素合成过程中的关键酶。柑橘、拟南芥、大白菜等多种植物β-羟化酶基因都已被克隆。柑橘中合成玉米黄素的中间产物β-隐黄素的含量远远高于其它植物,推测柑橘与其它植物的β-羟化酶基因相比有一些特殊的差异。本研究以南丰蜜橘为材料,克隆了柑橘β-羟化酶全长基因,并对该基因内含子进行定位和分析,结果表明南丰蜜橘β-羟化酶基因具有6个内含子,其中内含子6的长度远大于拟南芥和大白菜中相应的内含子。进一步研究发现内含子6中有两段特殊序列,一段长122 bp,另一段长95 bp。特别是122 bp序列两端具有反向重复序列,全序列中含有许多不同的转录起始原件。二级结构预测其对应RNA二级结构能构形成较稳定的发夹结构。

Plant β-carotene hydroxylase（β-hydroxylase）is a key enzyme in the process of zeaxanthin synthesis.β-hydroxylase genes of Citrus,Arabidopsis,Chinese cabbage and other plant have been cloned.β-cryptoxanthin is an intermediate product of synthetic zeaxanthin,and Citrus contain more β-cryptoxanthin than other plants.We speculate that β-hydroxylase gene from Citrus in comparison with other plants with special differences.In this study,Citrus β-hydroxylase full length gene was cloned from Nanfeng Orange,and the gene analysis and intron location showed that β-hydroxylase gene of Nanfeng Orange within 6 introns.The length of intron 6 is larger than the corresponding intron in Arabidopsis and Chinese cabbage.Further studies revealed that intron 6 has two special sequences,including a 122 bp long sequence and a 95 bp long sequence.Particularly,the 122 bp sequence ends with inverted repeat sequences,complete sequence of it contains a number of different transcription initiation original.Secondary structure prediction show that the secondary structure of the RNA corresponds to the 122 bp sequence has a stable hairpin structure.